Process for the isolation and characterisation of a gene enzyme system for inactivation of the herbicide phenmedipham and transfer of the gene into plants

ABSTRACT

A process for the isolation and characterization of a gene enzyme system for the inactivation of the herbicide phenmedipham, wherein the enzyme is a carbamate hydrolase of Arthrobacter oxidans, which is responsible for the cleavage of the carbamate bond between the benzene rings of phenmedipham. This process includes the isolation of the carbamate hydrolase, the identification of the amino acid sequence of two BrCN cleavage peptides of the carbamate hydrolase, the synthesis of oligonucleotides for specific determination of the carbamate hydrolase sequence by hybridization and identification of the coding region, cloning and specifying the nucleotide sequence of the carbamate hydrolase gene from Arthrobacter oxidans.

This application is a divisional of U.S. Ser. No. 07/615,448filed Nov. 19, 1990, now U.S. Pat. No. 5,347,076, which is a continuation-in-part of U.S. Ser. No. 07/353,871, filed on May 18, 1989, now abandoned.

The present invention relates to a process for the isolation and characterisation of a gene enzyme system for the inactivation of the herbicide phenmedipham and transfer of the gene into plants to produce herbicide-tolerant plants. The enzyme is a carbamate hydrolase of Arthrobacter oxidans, which is responsible for the cleavage of the carbamate bond between the benzene rings of phenmedipham which is the common name for the herbicide methyl 3-m-tolycarbamoyloxyphenyl-carbamate.

In practice it is often necessary to use several herbicides or herbicide mixtures to combat various weeds. These problems can be avoided by a biotechnical change to the plant in which resistance to a non-selective herbicide is introduced.

The production of herbicide-tolerant plants is now coming more to the foreground in the plant protection area.

In order to produce herbicide-tolerant plants, it is necessary first to have a process the isolation and subsequent purification of an enzyme which is able to inactivate a herbicide, eg by metabolism, and then to have a process for characterising the gene enzyme system containing the DNA sequence that codes for the active enzyme. After these steps the DNA sequence of the gene can be transferred into plants.

Such a process for the isolation and subsequent characterisation of a gene enzyme system which can inactivate phenmedipham and the transfer of this gene enzyme system into plants was not previously known.

It has now been found that a carbamate hydrolase can be isolated from some microorganisms, such as Arthrobacter oxidans, which is responsible for the hydrolysis of the carbamate bond between the two benzene rings of phenmedipham. The hydrolysis of this bond leads to herbicidally inactive compounds such as methyl 3-hydroxyphenylcarbamate and meta-toluidine, according to the following reaction: ##STR1## For isolation and subsequent purification of a gene enzyme system which can hydrolyse phenmedipham according to the above described reaction, microorganism of Arthrobacter oxidans are cultivated in a nutrient medium. The carbamate hydrolase responsible for the cleavage of phenmedipham is isolate by ultrasound cell destruction, centrifugation and purification by anion exchange chromalography, gradient elution, ammonium sulphate precipitation and FPLC separation until electrophoretic homogeneity is achieved. From the purified carbamate hydrolase, two peptides are isolated after BrCN cleavage whose sequence can be estimated by Edman degradation. According to the sequence information of these peptides, oligonucleotides can be synthesised which can be used as hybridization in probes for the detection of the carbamate hydrolase gene.

In all of the mentioned isolates of the soil bacteria Arthrobacter oxidans, plasmids could be detected after lysis of the cells and extraction of the nucleic acids.

For the species Arthrobacter oxidans P52, it can be shown that the carbamate hydrolase is coded by one plasmid.

With the loss of the plasmic pHP52 the properties of this species to be able to hydrolytically cleave phenmedipham is lost. Carbamate hydrolysis activity cannot be biochemically established in the plasmid-free derivative of the species p52.

The plasmid pHP52 can be preparatively isolate and mapped with restriction endonucleases. The electrophoretically separated restriction fragments can be transferred onto membrane filters and hydrodised with various oligonucleotides. From the data from the blot-hybridisations, it appears that the carbamate hydrolase gene is localised on a PstI restriction fragment with a size of 3.3 kb.

This fragment can be preparatively isolated from the plasmid pHP52 and inserted in the PstI position of the vector pUC19C (Yanish-Perron, C., Vieira, J. & Messing (1985) Gene 33, 103 ff). After transformation of E. coli DH5α with the ligation preparation, two types of recombinant E. coli clones are obtained (pp52Pst and pp52Pst inv.) which contain the carbamate hydrolase gene in different orientations to the Lac promoter of the vector (see FIG. 5).

The carbamate hydrolase can be functionally expressed in the presence of the inducer isopropyl-β-D-thiogalactopyranoside from cultures of the clone of the type E. coli DH5α (pp52Pst). In protein extracts of clones of the type E. coli DH5α (pp52 inc.) which contain the carbamate hydrolase gene in inverse orientation to the Lac promoter, no expression of the carbamate hydrolase gene can be detected.

The nucleotide sequence of the carbamate hydrolase gene can be determined according to the method of Sanger et al. (Sanger, F., Nicklen, S. & Coulson, A (1977), Proc. Natl. Acad. Sci. USA 74, 5463-5468).

15 sub-clones arising from the cloning of 3.3 kb long PstI restriction fragments can be constructed in the single strain DNA bacteriophages M13 mp 18 and mp 19 (Messing, ] (1983) Methods in Enzymol. 101, 20-78). In FIG. 6 an exact restriction map of the coded area is represented from which the sequencing strategy can be seen.

The established nucleotide sequence (SEQ ID NO: 7) with the protein sequence thus derived is illustrated in FIGS. 7, 7A and 7B (SEQ ID NO: 6). The amino acid sequences of both established BrCN-splitting peptides (see Example 4) can b identified in the same reading frame as the DNA level. This reading frame ends with a TGA translation stop codon (see FIG. 7, 7A and 7B, (SEQ ID NO: 6) nucleotide positions 1789-1791) and begins very probably with a GTG-start codon (FIGS. 7, 7A and 7B (SEQ ID NO: 6)--nucleotide positions 310-312. Altogether a reading frame of 1479 base pairs results. Upstream of the putative GTG-start codon, a region with significant homology to the consensus sequence for E. coli ribosome binding sites ("Shine-Dalgarno Box") can be established (see FIGS. 7, 7A and 7B, (SEQ ID NO: 6) nucleotide positions 298-302).

After the nucleotide sequence of the carbamate hydrolase gene has been determined, the construction of plasmids for the expression of carbamate hydrolase in plants can be carried out (see Example 9). For this the chimeric carbamate hydrolase gene on plasmids can be transferred from E. coli to Agrobacterium tumefaciens and from Agrobacterium tumefaciens to the target plants (see Example 10). The operation of the carbamate hydrolase gene in transformed plants can be shown by spraying transformed and untransformed plants with phenmedipham (see Examples 11 and 12).

On the 25th Aug. 1987 the following micro-organisms were deposited at the German Collection of Microorganisms (DSM) in Gottingen, Germany.

    ______________________________________                                         Arthrobacter oxidans                                                                          P 16/4/B    (DSM 4038)                                          Arthrobacter oxidans                                                                          P 67        (DSM 4039)                                          Arthrobacter oxidans                                                                          P 75        (DSM 4040)                                          Arthrobacter oxidans                                                                          P 11/1/-b   (DSM 4041)                                          Arthrobacter oxidans                                                                          P 15/4/A    (DSM 4045)                                          Arthrobacter oxidans                                                                          P 21/2      (DSM 4046)                                          Arthrobacter oxidans                                                                          P 52. containing the plasmid pHP52                                                   (DSM 4044).                                               ______________________________________                                    

Abbreviations

DEAE Diethylaminoethyl

FPLC Fast protein/peptide/polynucleotide liquid Chromatography

SDS Sodium lauryl sulphate

DTT Dithiothreitol

1×SSC 0.15M NaCl 0.015M trisodium citrate pH 7.0

1×Denhardt 0.02% (w/v) Bovine serum albumin (Sigma, Fraction V) 0.02% (w/v) Ficoll 400 0.02% polyvinylpyrrolidone

MCS Multiple cloning site

Abbreviation for Restriction Endonucleases

Bm=BamHI, Bs=BstEII, Cl=ClaI, EV=EcoRV, HII=HindII, Kp=KpnI, Nc=NcoI, Nd=NdeI, Nh=NheI, Ps=PstI, PvI=PvuI, PvII=PvuII, Sc=SacI, Sp=SphI, St=StuI, Xb=XbaI.

DESCRIPTION OF THE FIGURES

FIG. 1 shows the process for isolating and subsequent purification of phenmedipham cleaving carbamate hydrolase from Arthrobacter oxidans (Example 2).

FIG. 2 shows the electrophoretic separation of the crude extract and the isolation and pooled protein fractions after the individual purification steps on an SDS-polyacrylamide gel, in which standard proteins (M) run alongside as markers for the molecular weight.

A: Crude extract from the centrifuge supernatant of the ultrasound cell destruction of Arthrobacter oxidans.

B: Pooled protein fraction after gradient elution on a DEAE Sephacel column.

C: Ammonium sulphate precipitation of the fraction from B.

D: Protein fraction after gel filtration of the ammonium sulphate precipitation and subsequent separation on a Sephacryl S-300 column.

E: Protein fraction after separation of the pooled fraction from D by FPLC (anion exchange chromatography).

F: Protein fraction after separation of the pooled fraction E on a Superose 6 column (Example 2).

FIG. 3 shows a diagram from which the pH-optimum (pH 6.8) of the carbamate hydrolase can be obtained. The pH optimum can be established in such a way that the enzyme activity as a percentage against the pH value can be derived (Example 2).

FIG. 4 shows the restriction map of the plasmid pHP52 from the Arthrobacter oxidans (species P52).

FIG. 5 shows a scheme of cloning of the carbamate hydrolase gene. To improve clarity, the regions of the gene which hybridine with oligonucleotides used including the 5' and 3' flanking regions are enlarged above the ring-formed plasmid map.

The recombinant clones pp52Pst and pp52Pst inv. are represented in a linear manner. The transcription direction of the lac Z gene is represented by an arrow. ().

FIG. 6 shows the restriction map of the cloned 3.3 kb PstI restriction fragment which arises from the exact position of the carbamate hydrolase gene (Start: GTG=Start codon, Stop: TGA=Stop codon).

The sequenced areas are characterised by arrows under the restriction map. From the length of the arrow can be read the length of the individual sequenced areas.

The restriction fragments which contain the homology areas of the oligonucleotides described in Example 4 are emphasised in the map. ().

The M13 clones are described as follows:

    ______________________________________                                         Clone  Inserted Fragment     M13 Vector                                        ______________________________________                                         A      NdeI/SacI (pUC19)                                                                             ˜500   mp 18                                       B      NdeI/SacI      1289    bp   mp 18                                       C      PvuI/PstI      ˜700                                                                             bp   mp 19                                       D      PvuI/PvuI      564     bp   mp 18                                       E      BamHI/BamHI (pUC 19)  mp 18                                                                   ˜1060                                                                            bp                                               F      BamHI/BamHI    958     bp   mp 18                                       G      PvuI/PvuI      564     bp   mp 18                                       H      PvuII/SacI     476     bp   mp 18                                       I      ClaI/BamHI     561     bp   mp 18                                       K      ClaI/BamHI     397     bp   mp 18                                       L      PvuII/SacI     476     bp   mp 19                                       M      KpnI/HindII    445     bp   mp 19                                       N      BamHI/BamHI    958     bp   mp 18                                       O      BamHI/BamHI    1100    bp   mp 18                                       P      KpnI/HindII    445     bp   mp 18                                       ______________________________________                                    

FIGS. 7, 7A and 7B (SEQ ID NO: 6) shows the nucleotide sequence of the carbamate hydrolase gene including the 5' and 3' flanking area.

Particularly characterised are:

1. The GTG start codon

2. The ribosomal binding site (Shine-/Dalgarno Bos: S/D)

3. The homology area of the oligonucleotide described in Example 4 (oligo I and II/oligo III).

The coding nucleotide sequence was formally translated as an amino acid sequence. The reading frame is determined clearly by the protein level of the established amino acid partial sequences.

FIG. 8 shows the construction of plasmid pUPA1014. Starting from a 3.3 kb PstI fragment that originates from plasmid pHP52 (example 7) and contains the complete bacterial gene for phenmedipham carbamate hydrolase (PMPH), the untranslated 3'-region of the fragment is replaced by 0.2 kb fragment from the Agrobacterium tumefaciens T-DNA containing the octopine synthase gene (OCS) polyadenylation signal (pA). The vectors used are pUC19 (for pp52Pst) and pUC18 (for pA5 and pUPA1014).

FIG. 9 shows the construction of plasmid pUPO1015. In this cloning step the untranslated 5'-region and the N-terminal part of the coding region is removed from the carbamate hydrolase gene and replaced by a synthetic double-stranded oligonucleotide, which reconstitutes the sequence coding for the N-terminal part of the protein. The sequence surrounding the translational start codon is optimal for plant gene expression according to Lutcke et al. EMBO J. 6:43-48, 1987.

FIG. 10 shows the construction of plasmid pMCPO1021. In this cloning step, the coding sequence of the recombinant carbamate hydrolase gene is linked at its 5'-end to the cauliflower mosaic virus (CaMV) 35S promoter contained in plasmid pA8.

FIG. 11 shows the construction of plasmid pMA1017. In this cloning step a fragment containing the sequence hat codes for the potato proteinase inhibitor II signal peptide is inserted in correct orientation between the CaMV 35S promoter and the OCS polyadenylation signal of plasmid pA8 to create an expression vector for targeting introduced genes into the endoplasmatic reticulum of plant cells.

FIG. 12 shows the construction of plasmid pMAPO1022. In this cloning step the coding sequence of the recombinant carbamate hydrolase gene is linked at its 5'-end in the correct reading frame to the signal peptide sequence contained in plasmid pMA1017.

FIG. 13 shows transgenic tobacco plants WS28-19 in comparison with untransformed control tobacco W38 three weeks after treatment with the herbicide phenmedipham. FIG. 13A shows a control plant (left) which was sprayed with 1 kg/ha phenmedipham, a transformed plant (middle) which was sprayed with 1 kg/ha of phenmedipham and a transformed plant (right) which was not treated. FIG. 13B shows a control plant (left) which was sprayed with 1 kg/ha phenmedipham, a transformed plant (middle) which was sprayed with 3 kg/ha and a transformed plant (right) which was not treated. FIG. 13C shows a control plant (left) which was sprayed with 1 kg/ha phenmedipham, a transformed plant (middle) which was sprayed with 10 kg/ha and a transformed plant (right) which was not treated.

FIG. 14 shows transgenic tobacco plants WS28-19 in comparison with untransformed control tobacco W38 three weeks after treatment with the herbicide phenmedipham. FIG. 14 shows an untransformed control plant (left) and transformed plants (right) which were treated with 1 kg/ha phenmedipham (upper row), or left untreated (lower row), respectively.

FIG. 15 shows the relative variable fluorescence of intact leaves from a control W38 plant and a transgenic plant WS28-19 after treatment with 1 kg/ha phenmedipham. Measurements were made at indicated intervals after spraying (t=0) as described in the text. Between measurements plants were further incubated in the growth chamber under 16 hours light and 8 hours dark.

EXAMPLE 1

Isolation of microorganisms that possess the ability to inactive the herbicide phenmedipham.

To identify microorganisms which possessed the ability to inactivate the herbicide phenmedipham by metabolism, various microorganisms were screened. As source for the microorganisms, soil samples from various locations (filed test sites which had been treated several times with phenmedipham), and also from settling sediment, were used. Selection criteria for the identification of microorganisms which can carry out a carbamate cleavage, were as follows.

a) Growth in a nutrient medium with phenmedipham as a single carbon or nitrogen source.

b) Breaking down of phenmedipham to highly water soluble compounds according to the following reaction. ##STR2## From the large number of microorganisms obtained from the soil samples, which were capable of cleavage of phenmedipham, seven representatives were chosen which clearly showed a breakdown. These soil bacteria which are all representatives of the Arthrobacter species and within this species, the sub-species of oxidane, were cultivated in culture broths containing a synthetic medium (M9-medium) having the following composition:

1.0 g/l NH₄ Cl

0.25 g/l MgSO₄.7H₂ O

3.0 g/l KH₂ PO₄

7.0 g/l Na₂ HPO₄.2H₂ O

2.0 g/l Glucose and

0.5 g/l NaCl.

The M-9-medium, in addition, contained 1 mg/l thiamine (vitamin B1) as well as trace elements which were added in the form of a stock solution (1 ml/l M9-medium). The trace element stock solution contained:

0.5 Boric acid

0.04 g/l CuSO₄.5H₂ O

0.2 g/l FeCl₃.6H₂ O

0.4 g/l MnSO₄.7H₂ O

0.4 g/l ZnCl₂

0.2 g/l (NH₄)₆ Mo₇ O₂₄.4H₂ O

For shaking cultures in liquid mediums, the synthetic medium was supplemented by 0.1% casamino acids (Difco^(R)).

The soil bacteria were incubated in this M9 medium at 28° C. with good aeration until the end of the logarithmic growth phase. For enzyme purification, a total of 10 liters of medium were inoculated with a stationary pre-culture (1:100).

By HPLC analysis of the culture broth it was shown that in the cultures of Arthrobacter oxidans, the desired cleavage of phenmedipham to the herbicidally inactive products was achieved.

EXAMPLE 2

Isolation and purification of the carbamate hydrolase from Arthrobacter oxidans.

The isolation and subsequent purification of the carbamate hydrolase to electrophoretic homogeneity was carried out over a six stage purification process. From 6 liters of an end logarithmic culture of Arthrobacter oxidans (pHP52) (DSM No 4044), 0.5-1 mg carbamate hydrolase was reproducibly isolated. For isolation of the carbamate hydrolase, the cells were harvested by centrifugation (7000×g) and resuspended in about 40 ml of decomposition buffer (10 mM sodium phosphate pH 6.8 /1 mM DTT). The cell suspension was disrupted by ultrasound and homogenised at the same time. The homogenate was then centrifuged for 45 minutes at 40000×g, at 4° C. The sediment was removed and the supernatant, equilibrated with 100 mM Tris-HCl pH 7.2/100 mM NaCl/l mM DTT, was applied to a DEAE Sephacel column (column diameter 2.6 mm, height of the gel bed 20.5 cm. column volume about 100 ml). Before application to the column, the cell extract was diluted at a ratio of about 1:10 with starting buffer (100 mM Tris/100 mM NaCl/1 mM DTT). The column was then washed with starting buffer in order to remove the unbound material. The carbamate hydrolase was then eluted with a linear gradient 100 mM NaCl--500 mM NaCl (5×column volume). The enzymatically active fractions were pooled and treated with dry ammonium sulphate (NH₄)₂ SO₄ to an end concentration of 33% of the saturated solution. The resulting protein precipitate was sedimented by centrifugation (20000×g/30 mins) and discarded. The supernatant was treated with solid ammonium sulphate to an end concentration of 60% of the saturated solution and stirred for about 12 hours at 0° C. The sedimented protein was collected by centrifugation (20000×g/30 mins) and dissolved in about 1 ml starting buffer, treated with 10% (w/v) saccharose and loaded to a Sephacryl S-300 column. The gel filtration was carried out at a flow rate of 2.5 cm/h (elution buffer--: start buffer). The column had a diameter of 2.6 cm, a height of 95 cm and a volume of 475 ml. The enzymatically active fraction was then worked up on an FPLC column (mono Q HR 5/5: anion exchange). Gradient elution 100 mM NaCl--: 300 mM NaCl: flow rate: 0.5 ml/mm; application volume 2 ml). The unbound protein was separated by isocratic elution with 19 ml starting buffer. (Gradient elution 100 mM NaCl--: 300 mM NaCl in 20 ml with 100 mM Tris/HCl pH 7.2/1 mM DTT).

The enzymatically active fractions were concentrated by ultra-filtration after electrophoretic analysis of the purity (SDS-polyacrylamide-gel electrophoresis by the method of Lammli), using an Amicon.sup.(R), Centrikon 10 concentrator, and put on a FPLC gel-filtration column (Superose 6-HR 10/30, Pharmacia) (flow rate 0.2 ml/min; application volume 100 ul; eluent: 100 mM Tris/HCl pH 7.2/10 mM NaCl).

The active protein fractions which result from this step are electrophoretically homogenous.

The isolated enzyme is active in buffered solutions (ie buffers conventionally used in biochemical systems, such as phosphate buffers. Tris buffers etc: pH 6.8). Co-factors or metal ions are not necessary for the reaction. A sensitivity against SH reagents is also not seen. The optimum pH of the enzyme is 6.8.

The molecular weight of the carbamate hydrolase is in the range of 50-60, preferable 53-57 kd, both under denaturing/dissociating conditions (SDS gel electrophoresis) as well as under native conditions (gel-filtration). From this it follows that the carbamate hydrolase is a monomeric protein. The isoelectric point of the carbamate hydrolase is at pI=6.2.

EXAMPLE 3

Process for detecting the carbamate hydrolase.

For a quick and sure determination of enzyme activity during the purification of the crude protein extracts, an in vitro enzyme test was developed. The test is based on the ability of the enzyme to change the highly water insoluble phenmedipham into a soluble hydrolysis product. For this, solid phenmedipham was suspended in water and micronised by ultrasound. This micro-suspension was then poured, with stirring at 50° C., into an agarose solution and this mixture put into a petri dish before it solidified, where it formed into a turbid gel matrix. The enzyme solution was then put into wells which had been punched in the solid matrix. After incubation of the test plates for 2-4 hours at 30° C., the enzyme activity was demonstrated by observing clear zones in the matrix which had been made opaque by the phenmedipham.

EXAMPLE 4

Identification of the amino acid sequence of two BrCN cleaving peptides and synthesis of oligonucleotides for specific evidence of the carbamate hydrolase gene by hybridization.

Resulting from the purified carbamate hydrolase, two peptides were isolated after BrCN cleavage, whose partial sequence was established by Edman degradation.

BrCN Peptide I (SEQ ID NO: 1):

H₂ N--Ser--Asp--Glu--Phe--Ala--Asn--Leu--Asp--Arg--Trp--Thr--Gly--Lys--Pro--Phe--Val--Asp (Val)--Gly (His)--Leu--Asp--Glu--Val--Ala--Val--COOH

BrCN Peptide II (SEQ ID NO: 2):

N₂ H--Glu--His--Thr--Lys--Phe(Val)--Asn(Gly)--Glu--Arg)Cys)--Pro--Leu--Ala--Phe--Tyr--Pro--Val--Phe--Asn--Glu--COOH

According to the amino acid sequence information of these peptides, oligonucleotides were synthesised which could be used as hybridization probes for the detection of the carbamate hydrolase gene:

Oligonucleotide I (SEQ ID NO: 3) (17 mer "mixed probe") contains as the single strand DNA fragment, the sequence information of the BrCN peptide I amino acid position 10-15 (complementary strand). ##STR3##

Oligonucleotide II (SEQ ID NO: 4) (42 mer) contains as a single strand DNA fragment, the sequence information of the BrCN peptide I amino acid position 8-21 (complementary strand). The codon selection was carried out under the assumption of a guanine(G) and cytosine(C) rich DNA sequence (this takes into consideration guanine(G) and cytosine(C) nucleotides before adenine(A) and thiamine(T) nucleotides on the third position of the triplets). ##STR4##

Oligonucleotide III (SEQ ID NO: 5) contains as the single strand DNA fragment sequence, information of the BrCN peptide II (complementary strand). ##STR5##

By using these oligonucleotides it was possible to localise the carbamate hydrolase gene within the plasmid pHP52 by hybridization. For this, the plasmid DNA was cleaved with restriction endonucleases and the resulting fragments were separated by agarose gel electrophoresis and then transferred according to the method of E. M. Southern (J. Mol. Biol. 98, 503-517 (1975)) in single strand form on membrane filters (Gene Screen Plus ™ hybridising membrane. Du Pont de Nemours/NEW Research Products).

The oligonucleotides were and end marked by use of T4-polynucleotide kinase (Boehringer Mannheim) and [γ-³² P]-adenosine-5'-triphosphate (>5000 Ci/mmol, Du Pont de Nemours/NEN Research Products) using the method of R. B. Wallace and C. G. Miyada, Methods in Enzymology 152, 432-442 (1987) and treated without further purification for the hybridisation.

The hybridization was carried out using standard processes (P. J. Mason & J. G. Williams in "Nucleic Acid Hybridisation" p. 113-160 (1985) B. D. Hames & S. J. Higgins Hrsg. IRL Press Oxform, Washington D.C.). Under the conditions 6×SSC, 10×Denhardt, 0.5% w/v SDS and 100 u/ml t RNA (B±ckerhefe, Boehringer Mannheim), as well as 10 ng/ml marked oligonucleotides I/II/III at 41° C. (=6 hours), a specific hybridisation can be achieved. The detection of the hybrids was carried out by autoradiography (T Maniatis, E G Fritsch & J Sambrook, "Molecular Cloning", Cold Spring Harbor Laboratory (1982)).

EXAMPLE 5

Isolation and characterisation of the plasmid pHP52 from Arthrobacter oxidans P52.

For isolation of plasmid pH52 from Arthrobacter, the alkali extraction method of Birnboim and Doly (Birnboim H. C. & Doly J. (1979) Nucl Acid Res., 7, 1513-1523) was used, with a modification by Brandsch and Decker (Brandsch, R. & Decker, K. (1984) Arch. Microbiol. 138, 15-17). For plasmid preparation, the bacteria were cultivated in 6 of LB-medium comprising:

    ______________________________________                                         Bacto-trypton (Difco.sup.R)                                                                        10 g/l                                                     Bacto-Yeast-Extract (Difco.sup.R)                                                                   5 g/l                                                     NaCl                10 g/l                                                     ______________________________________                                    

to a cell density of OD₅₅₀ =1.4 and harvested by centrifuging.

The cells were resuspended in a total of 210 ml solution I (50 mM gluocose: 10 mM EDTA: 25 mM Tris/HCl, pH 8.0; 1 mg/ml lysosyme) and incubated for 1 hour at room temperature. Lysis was carried out by addition of 360 ml solution II (0.2M NaOH: 1% SDS). After gentle but thorough mixing and subsequent incubation for 5 minutes at room temperature, followed by cooling on ice for 5 minutes, the mixture was neutralised the addition of 180 ml solution III (2M Tris/HCl, pH 7.0/0.5M KCl. After incubation for 1 hour on ice, the undissolved precipitate was separated by centrifugation. The plasmid DNA was precipitated from the clear supernatant by addition of 0.6 volumes isopropanol and, after an incubation of 15 minutes at room temperature, pelleted by centrifugation (15,000×g/30 minutes). The plasmid-containing precipitate was dried in vacuo and dissolved in 24 ml 10×TE buffer (100 mM Tris/HCl, pH 8.0; 10 mM EDTA). This plasmid containing solution was then purified by isopycnic cesium chloride density gradient, centrifuging in the presence of Ethidium bromide (Maniatis T., Fritsch E. F. & Sambrook J. in "Molecular Cloning" (1982), Cold Spring Harbor N.Y.).

Purified plasmid DNA was mapped by restriction analysis which cut the plasmid once or gave several fragments. These fragments were resolved by agarose gel electrophoresis (0.8% w/v). Molecular weight standards used in mapping plasmid DNA were Hind III or Hind III and EcoRI digested bacteriophage DNA.

The restriction analysis data were consistent with a circular map of pHP52 (FIG. 4). The size of the plasmid is the sum of individual restriction fragments.

All the processes were carried out in this Example according to standard methods (cf. Maniatis T., Fritsch E. F. & Sambrook J. in "Molecular Cloning" Cold Spring Harbor, N.Y. (1982)).

EXAMPLE 6

Identification of the coding region of the carbamate hydrolase gene by oligonucleotide hybridisation.

By hybridisation of the restriction fragments of the plasmid pHP52 separated by gel electrophoresis and transferred on membrane filters with the ³² P marked oligonucleotide described in Example 4, the position of the coding region of the carbamate hydrolase gene can be definitely correlated on the restriction map of the plasmide pHP52. In FIG. 5, the hybridizing area is enlarged. All three oligonucleotides hybridize with the central part of a PstI restriction fragment of size 3.3 kb. In FIG. 6, a detailed restriction map of the fragment is shown from which the exact positions of the hybridising areas can be seen.

EXAMPLE 7

Cloning of the carbamate hydrolase gene is E. coli and demonstration of the genes' expression under lac promoter control.

For cloning the carbamate hydrolase gene in E. coli the vector pUC19 (Yanish-Perron, C., Vieira, J. & Messing, J. (1985) Gene 13, 103ff) was used. The pUC19 DNA was linearised by cleavage with restriction nuclease PstI and treated with alkaline phosphatase. The DNA of the 3.3 kb long PstI restriction fragment of the plasmid pHP52 was isolated (after digesting the wild-type plasmid DNA with PstI) by preparative agarose gel electrophoresis. The linearised and dephosphorylated vector DNA and the 3.3 kb long PstI fragment was then ligated with T4 DNA ligase. E. coli DH5α was transformed with the ligation mixture.

Two types of clones were obtained which contained the fragment in different orientations to the transcription direction of the lac Z' gene of the vector pUC 19. These are the clones pp52 Pst and pp52 Pst inv. The restriction map of both clones is shown in FIG. 5. The clones of type E. coli pp52 Pst express carbamate hydrolase. After addition of the inductor isopropyl-β-D-thiogalactopyranoside to the culture medium. Without inducer addition (repressed state of the lac promoter) to logarithmic cultures of the clone pp52 Pst as well as by repressed and induced logarithmic cultures of the clone pp52 Pst inv in enzyme extracts, no enzyme activity was seen using the assays described in Example 3.

This means that the carbamate hydrolase gene in clones of type pp52 Pst lies in the same transcription direction (5'-3' orientation) as the lac Z' gene of the vector. The Arthrobacter promoter is not or only slightly expressed in E. coli.

EXAMPLE 8

Nucleotide sequence of the carbamate hydrolase gene from the Arthrobacter oxidans (species P52) and the deduced protein sequence.

The nucleotide sequence of the carbamate hydrolase gene was established by the method of Sanger (Sanger F., Nicklen S. & Coulson A. (1977) Proc. Natl. Acad. Sci. USA, 74, 5463-5468).

For this, 15 sub-clones in the single stranded DNA bacteriophage M13 mp18 and M13 mp19 from the pp52 PST DNA were constructed (Messing, J. (1983) Methods in Enzymol. 101, 20-78). After transfection of E. coli DH5αF', the sequence of the single stranded recombinant DNA was established.

In FIG. 6, the sequencing strategy of the carbamate hydrolase gene is shown. Altogether the sequence of 1864 base pairs was established.

In FIGS. 7, 7A and 7B (SEQ ID NO: 6), the established nucleotide sequence is shown with the deduced amino acid sequence of the carbamate hydrolase. The reading frame is clearly defined as described by the amino acid sequences of two BrCN cleavage peptides as described in Example 4. The reading frame finishes with a TGA stop codon (nucleotide position 1789-1791 in FIGS. 7, 7A and 7B) (SEQ ID NO: 6). As a translation start codon, a GTG (nucleotide position 310-312) is suitable. This gives the longest open reading frame of 1479 bp (=493 amino acids). All open reading frame which begin with the usual ATG start codons give no protein of suitable size (compared to the molecular weight determination of the protein).

The hypothesis that translation starts from GTG (position 310-312) is further supported by the existence of a definite homologous region to the consensus sequence for ribosomal E. coli binding sites 7 bp upstream of the putative GTG start codon.

All cloning steps were carried out by standard processes (cf Maniatis, T., Fritsch, E. G. & Sambrook, J. (1982) in "Molecular Cloning", Cold Spring Harbor, N.Y.). The sequencing reactions were carried out using Sequenase^(R) DNA Sequencing Kits (United States Biochemical Corporation) according to information by the producer. The separation of the marked reaction products was carried in 6% w/v polyacrylamide/urea gel (Maxam, A. M. & Gilbert, W. (1980) Methods Enzymol. 65, 497-559).

EXAMPLE 9

Construction of plasmids for the expression of carbamate hydrolase in plants.

a) Construction of intermediate vectors

Plasmid DNA from pp52 Pst (FIG. 8) is methylated using TaqI Methylase (M. TaqI) to make the single SaII restriction site inaccessible to HincII. Then the methylated plasmid is cut with both restriction enzymes XbaI and HincII to release a 2.2 kb DNA fragment containing the open reading frame for carbamate hydrolase. This fragment is purified by preparative agarose gel electrophoresis. The vector plasmid pA5 (FIG. 8) is cut with XbaI and HincII and then ligated with the purified 2.2 kb DNA fragment, thus linking the 3'-end of the carbamate hydrolase coding region to the polyadenylation signal of the octopine synthetase (OCS) gene (Dhaese et al., EMBO J. 2:419, 1983). Competent cells of E. coli DH5alpha are transformed with the recombined DNA and clones are selected on LB-agar containing 100 μg/ml carbenicillin. Clones containing the recombined plasmid pUPA1014 (FIG. 8) are identified by restriction analysis of isolated plasmid DNA.

Two oligonucleotides of the following sequence are synthesized by an automatic synthesizer:

1.) 5'-CTAGAGATCT CAACAATGGT TACCAGACCG ATCGCCCACA CCACCGCTGG G-3' (SEQ ID NO: 8)

2.) 5'-GTCCCCAGCG GTGGTGTGGG CGATCGGTCT GGTAACCATT GTTGAGATC-3' (SEQ ID NO: 9)

They represent complementary DNA strands which are able to reconstitute the N-terminal portion of the open reading frame of the carbamate hydrolase gene upstream (5') of the PpuMI restriction site.

Both complementary oligonucleotides are mixed, phophorylated by polynucleotide kinase and then annealed by shifting temperature from 70° C. to room temperature overnight. Plasmid DNA of pUPA1014 is digested with XbaI and then ligated with the annealed oligonucleotide. This covalently links two oligonucleotides at their XbaI-compatible ends to both ends of the linearised plasmid. The linear ligation product is purified by preparative agarose gel electrophoresis and digested with PpuMI to remove the N-terminal part of the coding region. The linear DNA is then recircularized by ligase treatment. Competent cells of E. coli DH5alpha are transformed with the recombined DNA and clones are selected on LB-agar containing 50 ug/ml carbenicillin. Clones containing the recombined plasmid pUP01015 (FIG. 9) are identified by restriction analysis of isolated plasmid DNA. The correct ligation of the oligonucleotide is verified by sequence analysis of purified pUP01015 DNA using the dideoxy method (Sanger et al., Proc. Natl. Acad. Sci. USA 74:5463, 1977) modified for plasmid DNA as template (Chen and Seeburg, DNA 4:165, 1985).

b) Construction of plasmids for the cytoplasmatic expression of carbamate hydrolase.

Plasmid DNA of pUP010115 is digested with both restriction enzymes XbaI and HindIII to create a DNA fragment that contains the whole recombinant coding region of the carbamate hydrolase together with the polyadenylation signal described above. The fragment is then ligated with the plant expression vector plasmid pA8 (A. v. Schaewen, Dissertation, FU Berlin, 1989; FIG. 10) which was similarily treated with XbaI and HindIII. The ligation links the gene in correct orientation to the cauliflower mosaic virus (CaMV) 35S promoter (Paszkowski et al., EMBO J. 3:2717, 1984) contained in pA8. Competent cells of E. coli DH5alpha are transformed with the recombined DNA and clones are selected on LB-agar containing 25 μg/ml streptomycin. Clones containing the recombined plasmid pMCPO1021 (FIG. 10) are identified by restriction analysis of isolate plasmid DNA.

Plasmid DNA of pMCPO1021 is digested with both restriction enzymes EcoRI and HindIII to create a DNA fragment that contains the CaMV 35S promoter, the carbamate hydrolase coding region and the OCS polyadenylation signal. The fragment is then ligated with a EcoRI and HindIII cleaved vector plasmid pBIN19 that is part of the binary transformation system described by Bevan, Nucl. Acids Rec. 12:8711, 1984. Competent cells of E. coli S17-1 (Simon et al. Bio/Technology 1:784-791, 1983) are transformed with the recombined DNA and clones are selected on LB-agar containing 50 μg/ml kanamycin. Clones containing the recombined plasmid pBCPO1027 are identified by restriction analysis of isolated plasmid DNA.

c) Construction of plasmids for the extracellular expression of carbamate hydrolase.

Plasmid pA22 (FIG. 11) contains a synthetic intronless sequence that codes for the signal peptide of the proteinase inhibitor II (PI) from potato and can be attached to the N-terminus of other genes to direct the gene product into the endoplasmatic reticulum of the plant cell. To create an intermediate vector for targeting of carbamate hydolase, the DNA fragment encoding the signal peptide is excised from plasmid pA22 by cleavage with restriction enzymes KpnI and XbaI and then ligated with a KpnI and XbaI cleaved plasmid pA8. Competent cells of E. coli DH5alpha are transformed with the recombined DNA and clones are selected on LB-agar containing 25 μg/ml streptomycin. Streptomycin resistant clones are then screened for the loss of plasmid pA22 on LB-agar containing 50 μg/ml carbenicillin. Carbenicillin sensitive clones are analyzed by restriction analysis of isolated plasmid DNA and recombined plasmids containing the signal peptide encoding sequence are designated pmA 1017 (FIG. 11).

Plasmid DNA of pUP01015 id digested with both restriction enzymes HindIII and BgIII to create a DNA fragment that contains the whole recombinant coding region of the carbamate hyrolase together with the polyadenylation signal described above. The fragment is then ligated with the plant expression vector plasmid pMA1017 which has been digested with BamHI and HindIII. The ligation links the gene in correct orientation to the cauliflower mosaic virus (CaMV) 35S promoter (Paszkowski et al., EMBO J. 3:2717, 1984) and the proteinase inhibitor signal sequence described above. Competent cells of E. coli DH5alpha are transformed with the recombined DNA and clones are selected on LB-agar containing 25 μg/ml streptomycin. Clones containing the recombined plasmid pMAP01022 (FIG. 12) are identified by restriction analysis of isolated plasmid DNA.

Plasmid DNA of pMAP010122 is digested with both restriction enzymes EcoRI and HindIII to create a DNA fragment that contains the CaMV 35S promoter, the PI signal sequence linked in frame to the carbamate hydrolase coding region and the OCS polyadenylation signal. The fragment is then ligated with a EcoRI and HindIII cleaved vector plasmid pBIN19 (Bevan, Nucl, Acids Res. 12:8711, 1984). Competent cells of E. coli S17-1 (Simon et al. Bio/Technology 1:784-791, 1983) are transformed with the recombined DNA and clones are selected on LB-agar containing 50 μg/ml kanamycin. Clones containing the recombined plasmid pBAP01027 are identified by restriction analysis of isolated plasmid DNA.

EXAMPLE 10

Transformation of tobacco with chimeric carbamate hydrolase genes

a) Transfer of recombinant carbamate hydrolase from E. coli to A. tumefaciens

Strains of E. coli S17-1 containing chimeric carbamate hydrolase gene on plasmids pBCPO1027 or pBAP01028 are grown at 37° C. in liquid LB medium containing 50 μg/ml kanamycin. Agrobacterium tumefaciens LBA4404 (Bevan, Nucl. Acids Res. 12:8711, 1984) is grown at 28° C. in liquid YEB medium (Yeast extract 1 g/l, beef extract 5 g/l, peptone 5 g/l, sucrose 5 g/l, sucrose 5 g/l, MgSO₄ 0.5 g/l). 0.4 ml samples of E. coli culture are centrifuged and the bacterial pellets are resuspended in 0.4 ml YEB. Bacterial suspensions of E. coli in YEB and samples of Agrobacterium tumefaciens culture in YEB are then mixed in a 1:1 ratio in relation to cell density. Samples 50-100 μl from the mixtures are spotted onto LB-agar and incubated at 28° C. for 6-16 hours. Bacterial mating mixtures that have grown on the agar are suspended in liquid M9-salts (6 g/l Na₂ HPO₄, 3 g/l KH₂ PO₄, 0.5 g/l NaCl, 1 g/l NH₄ Cl. 2 mM MgSO₄, 0.1 mM CaCl₂, 1 mM HCl) and then plated in several dilutions onto M9-agar containing 2 g/l sucrose and 50 μg/ml kanamycin. Plates are incubated at 28° C. for several days until bacterial colonies have grown. These colonies are further purified by subsequent cultivation on the same medium. That these clones of A. tumefaciens LBA4404 contain recombinant plasmids pBCPO1027 and pBAP01028 respectively is verified by restriction analysis of isolated plasmid DNA.

b) Transfer of recombinant carbamate hyrolase from A. tumefaciens to tobacco.

For transformation of tobacco, A. tumefaciens strains harbouring carbamate hydrolase plasmids are grown overnight at 28° C. in liquid YEB medium containing 50 μg/ml kanamycin. Cells are centrifuged at 5000 g for 15 minutes and resuspended in the same volume of YEB without antibiotic. Nicotians tabacum Wisconsin W38 plantlets are grown under sterile conditions on solid MS medium containing 20 g/l sucrose. Leaves are cut from those plants, dissected into pieces of around 1 cm² and rinsed with the bacterial suspension. Leaf disks are then placed onto solid MS medium containing 20 g/l sucrose. After 2 days of incubation at room temperature in the dark leaf disks are transferred to solid MS medium containing 16 g/l glucose, 1 mg/l benzylaminopurine, 0.2 mg/l naphthylacetic acid, 500 mg/l claforan and 50 mg/l kanamycin. Incubation is continued at 25° C. under a daily regime of 16 hours light (photosynthetically active radiation=67 μEM⁻² s⁻¹) and 8 hours dark. The medium is changed every week until shoots appear. These are cut from the callus and transferred to MS medium containing 20 g/l sucrose and 250 mg/l claforan. Incubation is continued under the same conditions until roots of 1-2 cm in length have formed and plants are transferred to soil. Total RNA isolated from leaves is analyzed by northern blot hybridisation using the 1.8 kb EcoRI-HindIII fragment of pUPO1015 as a labeled probe. Transformed plants synthesize a transcript of around 1.8 kb in size that specifically hybridizes with the carbamate hydrolase coding sequence.

EXAMPLE 11

Detection of transformed plants which are resistant to the herbicidal activity of phenmedipham.

Transgenic plants are transferred to soil and grown in a growth chamber at 25° C. with a day/night rhythm of 16 hours light and 8 hours dark. No difference in growth can be seen between transformed and untransformed tobacco. Plants that have a leaf length of around 10 cm are sprayed with the herbicide Betanal® (active ingredient: 157 g/l phenmedipham).

Doses corresponding to field application rates of 1 kg/ha. 3 kg/ha and 10 kg/ha are used to distinguish between resistant plants and untransformed wildtype plants: Whereas 1 kg/ha is completely lethal for wildtype plants, transgenic plants which express the carbamate hydrolase gene show resistance levels between 1 kg/ha and 10 kg/ha (FIG. 13 and 14).

The same spraying experiment is done by using Betanal® AM (active ingredient: 157 g/l desmedipham) as the herbicidal agent.

EXAMPLE 12

Analysis of herbicide detoxification in plants sprayed with phenmedipham.

Transgenic tobacco plants expressing carbamate hydrolase and untransformed control plants are grown as described in example 11 and sprayed with the herbicide Betanal® corresponding to 1 kg/ha phenmedipham. Normalized variable fluorescence is measured on intact leaves of sprayed plants as is described by Voss. Weed Science 32:675-680 (1984). The equipment used is a Kompakt-Fluorometer RKF 1000 (Ingenieurburo F.U.R. Dr. M. Voss, Berlin). Measurement values before spraying are taken as 100% relative variable fluorescence. Subsequent measurements are performed in a time course of 2, 4, 8, 24 hours and then very day up to 4 days. Relative variable fluorescence values of transgenic tobacco plants expressing carbamate hydrolase stay constantly higher than 90% in contrast values from untransformed tobacco fall below

10% within the first 8 hours after spraying (FIG. 15).

The same spraying experiment is done by using Betanal® AM (active ingredient: 157 g/l desmedipham) as the herbicidal agent.

    __________________________________________________________________________     SEQUENCE LISTING                                                               (1) GENERAL INFORMATION:                                                       (iii) NUMBER OF SEQUENCES: 9                                                   (2) INFORMATION FOR SEQ ID NO:1:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 24 amino acids                                                     (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (iii) HYPOTHETICAL: NO                                                         (iv) ANTI-SENSE: NO                                                            (v) FRAGMENT TYPE: internal                                                    (vi) ORIGINAL SOURCE:                                                          (A) ORGANISM: Arthrobacter oxidans                                             (B) STRAIN: P52                                                                (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:                                        SerAspGluPheAlaAsnLeuAspArgTrpThrGlyLysProPheVal                               151015                                                                         XaaXaaLeuAspGluValAlaVal                                                       20                                                                             (2) INFORMATION FOR SEQ ID NO:2:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 18 amino acids                                                     (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (iii) HYPOTHETICAL: NO                                                         (iv) ANTI-SENSE: NO                                                            (v) FRAGMENT TYPE: internal                                                    (vi) ORIGINAL SOURCE:                                                          (A) ORGANISM: Arthrobacter oxidans                                             (B) STRAIN: P52                                                                (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:                                        GluHisThrLysXaaXaaGluXaaProLeuAlaPheTyrProValPhe                               151015                                                                         AsnGlu                                                                         (2) INFORMATION FOR SEQ ID NO:3:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 17 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: DNA (genomic)                                              (iii) HYPOTHETICAL: YES                                                        (iv) ANTI-SENSE: NO                                                            (vi) ORIGINAL SOURCE:                                                          (A) ORGANISM: Arthrobacter oxidans                                             (B) STRAIN: P52                                                                (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:                                        AANGGYTTNCCNGTCCA17                                                            (2) INFORMATION FOR SEQ ID NO:4:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 42 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: DNA (genomic)                                              (iii) HYPOTHETICAL: YES                                                        (iv) ANTI-SENSE: NO                                                            (vi) ORIGINAL SOURCE:                                                          (A) ORGANISM: Arthrobacter oxidans                                             (B) STRAIN: P52                                                                (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:                                        CTGGTCCAGGCCGTCCACGAACGGCTTGCCGGTCCAGCGGTC42                                   (2) INFORMATION FOR SEQ ID NO:5:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 24 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: DNA (genomic)                                              (iii) HYPOTHETICAL: YES                                                        (iv) ANTI-SENSE: NO                                                            (vi) ORIGINAL SOURCE:                                                          (A) ORGANISM: Arthrobacter oxidans                                             (B) STRAIN: P52                                                                (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:                                        TTCGTTGAAGACCGGGTAGAACGC24                                                     (2) INFORMATION FOR SEQ ID NO:6:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 1864 base pairs                                                    (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: double                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: DNA (genomic)                                              (iii) HYPOTHETICAL: NO                                                         (iv) ANTI-SENSE: NO                                                            (ix) FEATURE:                                                                  (A) NAME/KEY: RBS                                                              (B) LOCATION: 298..302                                                         (ix) FEATURE:                                                                  (A) NAME/KEY: CDS                                                              (B) LOCATION: 310..1791                                                        (D) OTHER INFORMATION: /codon=(seq: "gta", aa: Val)                            /product="carbamate hydrolase"                                                 /transl.sub.-- except=(pos: 310 .. 312, aa: Met)                               /note="terminator (1789-1791)"                                                 (ix) FEATURE:                                                                  (A) NAME/KEY: mat.sub.-- peptide                                               (B) LOCATION: 310..1788                                                        (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:                                        TCCTTGCCAGTCACGGCACCCCAGCCAACCCGGAAGTGGCACCTGCTCGGGCACATCGGT60                 GCGAACGCTTCGTCCTGATTCCGATGCCAACTGCTTGACGGCCGTGACACATATGTAGCA120                TAGTCGCCTAGCATGGACCCGCAGCACACCTGCTGTCGGCTCCCGCGCTATCCCCGACCA180                GCGCCGGTCACGGGTAGTCCTCGTGAGAGGCACCAGAACGACAACGGCGCACTGTCCCGC240                AACACGGCCGTATAACCCCACCGGGGTCCGCGCCCGAGCTAGTTCTGGCTCAACCATAAG300                GAGAACCTCGTGATTACCAGACCGATCGCCCACACCACCGCTGGGGAC348                            MetIleThrArgProIleAlaHisThrThrAlaGlyAsp                                        1510                                                                           CTCGGCGGTTGCCTTGAAGACGGCCTGTACGTGTTCCGAGGAGTGCCG396                            LeuGlyGlyCysLeuGluAspGlyLeuTyrValPheArgGlyValPro                               152025                                                                         TACGCCGAGCCGCCGGTCGGCGACCTGCGGTGGCGGGCGGCGCGCCCG444                            TyrAlaGluProProValGlyAspLeuArgTrpArgAlaAlaArgPro                               30354045                                                                       CACGCCGGCTGGACCGGCGTCCGCGACGCCTCCGCGTATGGTCCCTCG492                            HisAlaGlyTrpThrGlyValArgAspAlaSerAlaTyrGlyProSer                               505560                                                                         GCGCCGCAACCCGTGGAGCCTGGCGGCTCGCCGATCCTTGGGACACAC540                            AlaProGlnProValGluProGlyGlySerProIleLeuGlyThrHis                               657075                                                                         GGCGACCCTCCGTTTGACGAGGACTGCCTGACTCTCAATCTTTGGACC588                            GlyAspProProPheAspGluAspCysLeuThrLeuAsnLeuTrpThr                               808590                                                                         CCGAACCTCGACGGCGGTAGCCGGCCGGTCCTCGTCTGGATCCATGGT636                            ProAsnLeuAspGlyGlySerArgProValLeuValTrpIleHisGly                               95100105                                                                       GGGGGCCTACTAACCGGCTCGGGAAATCTACCTAACTACGCGACCGAT684                            GlyGlyLeuLeuThrGlySerGlyAsnLeuProAsnTyrAlaThrAsp                               110115120125                                                                   ACCTTCGCCCGCGACGGCGACTTGGTAGGTATCTCAATCAATTACCGG732                            ThrPheAlaArgAspGlyAspLeuValGlyIleSerIleAsnTyrArg                               130135140                                                                      CTCGGGCCTCTTGGATTCCTCGCAGGAATGGGCGACGAGAATGTCTGG780                            LeuGlyProLeuGlyPheLeuAlaGlyMetGlyAspGluAsnValTrp                               145150155                                                                      CTCACCGATCAGGTAGAGGCACTGCGCTGGATTGCAGATAACGTTGCT828                            LeuThrAspGlnValGluAlaLeuArgTrpIleAlaAspAsnValAla                               160165170                                                                      GCCTTCGGTGGAGACCCGAACCGGATCACTCTCGTCGGTCAATCAGGC876                            AlaPheGlyGlyAspProAsnArgIleThrLeuValGlyGlnSerGly                               175180185                                                                      GGGGCATACTCGATCGCAGCGCTCGCCCAACACCCGGTCGCCCGTCAG924                            GlyAlaTyrSerIleAlaAlaLeuAlaGlnHisProValAlaArgGln                               190195200205                                                                   CTGTTCCACCGCGCGATCCTACAAAGCCCACCATTCGGGATGCAACCC972                            LeuPheHisArgAlaIleLeuGlnSerProProPheGlyMetGlnPro                               210215220                                                                      CATACAGTTGAAGAATCGACGGCAAGGACGAAGGCCCTGGCCCGGCAT1020                           HisThrValGluGluSerThrAlaArgThrLysAlaLeuAlaArgHis                               225230235                                                                      CTCGGGCACGATGACATCGAGGCCCTGCGCCATGAGCCGTGGGAGAGG1068                           LeuGlyHisAspAspIleGluAlaLeuArgHisGluProTrpGluArg                               240245250                                                                      CTGATTCAAGGCACGATAGGCGTCCTGATGGAACACACCAAATTTGGC1116                           LeuIleGlnGlyThrIleGlyValLeuMetGluHisThrLysPheGly                               255260265                                                                      GAATGGCCCCTGGCATTCTATCCGGTGTTCGATGAGGCAACGATACCT1164                           GluTrpProLeuAlaPheTyrProValPheAspGluAlaThrIlePro                               270275280285                                                                   CGCCATCCGATTGAGTCCATTATCGATTCCGACATCGAAATCATCATC1212                           ArgHisProIleGluSerIleIleAspSerAspIleGluIleIleIle                               290295300                                                                      GGCTGGACACGCGACGAGGGCACTTTTCCGTTTGCCTTCGACCCTCAG1260                           GlyTrpThrArgAspGluGlyThrPheProPheAlaPheAspProGln                               305310315                                                                      GTTTCACAGGCGGATCGCGATCAGGTCGAGTCATGGTTGCAGAAGCGT1308                           ValSerGlnAlaAspArgAspGlnValGluSerTrpLeuGlnLysArg                               320325330                                                                      TTCGGAGACCACGCCGCCTCGGCCTACGAGGCTCACGCCGGCGACGGA1356                           PheGlyAspHisAlaAlaSerAlaTyrGluAlaHisAlaGlyAspGly                               335340345                                                                      ACCAGTCCTTGGACCGTTATCGCCAACGTTGTGGGCGACGAGCTCTTT1404                           ThrSerProTrpThrValIleAlaAsnValValGlyAspGluLeuPhe                               350355360365                                                                   CACAGCGCTGGGTACCGGGTCGCGGACGAACGGGCAACGCGCAGACCG1452                           HisSerAlaGlyTyrArgValAlaAspGluArgAlaThrArgArgPro                               370375380                                                                      GTACGGGCCTATCAGTTCGACGTAGTCTCGCCCTTGTCGGACGGAGCC1500                           ValArgAlaTyrGlnPheAspValValSerProLeuSerAspGlyAla                               385390395                                                                      CTCGGCGCGGTCCACTGCATCGAAATGCCGTTCACATTTGCCAATCTC1548                           LeuGlyAlaValHisCysIleGluMetProPheThrPheAlaAsnLeu                               400405410                                                                      GACCGTTGGACGGGGAAGCCGTTCGTGGACGGCCTGGATCCAGACGTG1596                           AspArgTrpThrGlyLysProPheValAspGlyLeuAspProAspVal                               415420425                                                                      GTGGCTCGGGTGACCAACGTGTTGCATCAGGCCTGGATCGCATTCGTC1644                           ValAlaArgValThrAsnValLeuHisGlnAlaTrpIleAlaPheVal                               430435440445                                                                   CGAACGGGAGACCCCACGCACGACCAGTTGCCGGTGTGGCCAACGTTC1692                           ArgThrGlyAspProThrHisAspGlnLeuProValTrpProThrPhe                               450455460                                                                      CGAGCGGACGACCCAGCGGTGTTGGTCGTCGGCGACGAGGGAGCAGAG1740                           ArgAlaAspAspProAlaValLeuValValGlyAspGluGlyAlaGlu                               465470475                                                                      GTGGCGCGGGATCTAGCGCGCCCGGACCACGTCAGCGTTCGGACCCTA1788                           ValAlaArgAspLeuAlaArgProAspHisValSerValArgThrLeu                               480485490                                                                      TGAGGGTCGCGGGTCGCCGGGGTCTTGAGGCCGGAGGGCCTCGCGTATGCAGTGATTCGT1848               GGATCACCGGCCAGTT1864                                                           (2) INFORMATION FOR SEQ ID NO:7:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 493 amino acids                                                    (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:                                        MetIleThrArgProIleAlaHisThrThrAlaGlyAspLeuGlyGly                               151015                                                                         CysLeuGluAspGlyLeuTyrValPheArgGlyValProTyrAlaGlu                               202530                                                                         ProProValGlyAspLeuArgTrpArgAlaAlaArgProHisAlaGly                               354045                                                                         TrpThrGlyValArgAspAlaSerAlaTyrGlyProSerAlaProGln                               505560                                                                         ProValGluProGlyGlySerProIleLeuGlyThrHisGlyAspPro                               65707580                                                                       ProPheAspGluAspCysLeuThrLeuAsnLeuTrpThrProAsnLeu                               859095                                                                         AspGlyGlySerArgProValLeuValTrpIleHisGlyGlyGlyLeu                               100105110                                                                      LeuThrGlySerGlyAsnLeuProAsnTyrAlaThrAspThrPheAla                               115120125                                                                      ArgAspGlyAspLeuValGlyIleSerIleAsnTyrArgLeuGlyPro                               130135140                                                                      LeuGlyPheLeuAlaGlyMetGlyAspGluAsnValTrpLeuThrAsp                               145150155160                                                                   GlnValGluAlaLeuArgTrpIleAlaAspAsnValAlaAlaPheGly                               165170175                                                                      GlyAspProAsnArgIleThrLeuValGlyGlnSerGlyGlyAlaTyr                               180185190                                                                      SerIleAlaAlaLeuAlaGlnHisProValAlaArgGlnLeuPheHis                               195200205                                                                      ArgAlaIleLeuGlnSerProProPheGlyMetGlnProHisThrVal                               210215220                                                                      GluGluSerThrAlaArgThrLysAlaLeuAlaArgHisLeuGlyHis                               225230235240                                                                   AspAspIleGluAlaLeuArgHisGluProTrpGluArgLeuIleGln                               245250255                                                                      GlyThrIleGlyValLeuMetGluHisThrLysPheGlyGluTrpPro                               260265270                                                                      LeuAlaPheTyrProValPheAspGluAlaThrIleProArgHisPro                               275280285                                                                      IleGluSerIleIleAspSerAspIleGluIleIleIleGlyTrpThr                               290295300                                                                      ArgAspGluGlyThrPheProPheAlaPheAspProGlnValSerGln                               305310315320                                                                   AlaAspArgAspGlnValGluSerTrpLeuGlnLysArgPheGlyAsp                               325330335                                                                      HisAlaAlaSerAlaTyrGluAlaHisAlaGlyAspGlyThrSerPro                               340345350                                                                      TrpThrValIleAlaAsnValValGlyAspGluLeuPheHisSerAla                               355360365                                                                      GlyTyrArgValAlaAspGluArgAlaThrArgArgProValArgAla                               370375380                                                                      TyrGlnPheAspValValSerProLeuSerAspGlyAlaLeuGlyAla                               385390395400                                                                   ValHisCysIleGluMetProPheThrPheAlaAsnLeuAspArgTrp                               405410415                                                                      ThrGlyLysProPheValAspGlyLeuAspProAspValValAlaArg                               420425430                                                                      ValThrAsnValLeuHisGlnAlaTrpIleAlaPheValArgThrGly                               435440445                                                                      AspProThrHisAspGlnLeuProValTrpProThrPheArgAlaAsp                               450455460                                                                      AspProAlaValLeuValValGlyAspGluGlyAlaGluValAlaArg                               465470475480                                                                   AspLeuAlaArgProAspHisValSerValArgThrLeu                                        485490                                                                         (2) INFORMATION FOR SEQ ID NO:8:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 51 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: DNA (genomic)                                              (iii) HYPOTHETICAL: NO                                                         (iv) ANTI-SENSE: NO                                                            (vi) ORIGINAL SOURCE:                                                          (A) ORGANISM: Arthrobacter oxidans                                             (B) STRAIN: P52                                                                (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:                                        CTAGAGATCTCAACAATGGTTACCAGACCGATCGCCCACACCACCGCTGGG51                          (2) INFORMATION FOR SEQ ID NO:9:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 49 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: DNA (genomic)                                              (iii) HYPOTHETICAL: NO                                                         (iv) ANTI-SENSE: NO                                                            (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:                                        GTCCCCAGCGGTGGTGTGGGCGATCGGTCTGGTAACCATTGTTGAGATC49                            __________________________________________________________________________ 

We claim:
 1. Oligonucleotides having the nucleotide sequences:Nucleotide I (SEQ ID NO:8): 5'-CTAGAGATCT CAACAATGGT TACCAGACCG ATCGCCCACA CCACCGCTGG G-3' Nucleotide II (SEQ ID NO:9): ' -GTCCCCAGCG GTGGTGTGGG CGATCGGTCT GGTAACCATT GTTGAGATC-3'.
 2. A method for the reconstitution of the N-terminal portion of the open reading frame of a carbamate hydrolase gene upstream (5') of the PpuMI restriction site, wherein said method comprises the step of:ligating oligonucleotides to said carbamate hydrolase gene, wherein the oligonucleotides comprise: Nucleotide I (SEQ ID NO: 8): 5'-CTAGAGATCT CAACAATGGT TACCAGACCG ATCGCCCACA CCACCGCTGG G-3' and Nucleotide I (SEQ ID NO: 9): 5'-GTCCCCAGCG GTGGTGTGGG CGATCGGTCT GGTAACCATT GTTGAGATC-3'.
 3. A purified and isolate carbamate hydrolase gene capable of inactivating phenmedipham.
 4. A vector comprising oligonucleotides, wherein the oligonucleotides comprise:Nucleotide I (SEQ ID NO: 8): 5'CTAGAGATCT CAACAATGGT TACCAGACCG ATCGCCCACA CCACCGCTGG G-3'; and Nucleotide II (SEQ ID NO: 9): 5'-GTCCCCAGCG GTGGTGTGGG CGATCGGTCT GGTAACCATT GTTGAGATC-3'.
 5. The purified and isolated carbamate hydrolase gene according to claim 3, wherein the carbamate hydrolase gene has the activity of a carbamate hydrolase from Arthrobacter oxidans when it is expressed. 